I 9 o8] SHULLMENDELIAN INHERITANCE 109 



During the summer of 1905 experiments were also begun for the 

 purpose of testing the relationship between the Russian sunflower 

 and the wild Helianthus annuus of the prairie region. Seed of the 

 latter had been received from Nebraska through the kindness of Dr. 

 C. E. BESSEY. Several points of contrast were noted between the 

 plants produced from this seed and the Russian sunflower, the most 

 noteworthy being with regard to branching habit and the color of the 

 disk. The lower branches of the wild sunflower, when given space 

 for full individual expression as they are in my cultures, diverge 

 almost horizontally, having on this account a slightly wider spread 

 than branches arising at higher points on the stem. At the time the 

 first head is ready to spread its rays, the whole plant has a nearly 

 conical form. The development of the primary head checks the 

 growth of the main stem, and some of the upper branches then usually 

 elongate so as to overtop the central axis, thus giving the mature 

 plant a more columnar form. My branched type of the Russian 

 sunflower has all the branches strongly ascending, the lower being 

 enough longer than the upper to reach almost the same level, thus 

 giving the mature plant a corymbose or broadly obconical form. 



I have not yet reached a conclusion in regard to the hereditary 

 behavior of these two types of branching, as it is not easy to find 

 decisive criteria for the exact classification of the two forms and their 

 combinations. It has been apparent, however, in my cultures that 

 there is a combination of both types of branching in many if not all 

 of the first-generation hybrids, and at least some segregation in the 

 next generation. The indefiniteness of the character will probably 

 make it difficult to reach satisfactory quantitative results, but the 

 attempt is being made. 



A very much simpler character to deal with is the color of the disk. 

 All of the western Helianthus annuus that I have thus far observed 

 have a deep purple disk, the color being found in the tips of the 

 paleae, which are of a deep, metallic purple; the margin of the corolla, 

 which is brownish purple ; and the style and stigmas, which are reddish 

 purple. In all my Russian sunflowers, the tips of the paleae are 

 yellowish green, the corolla is a clear lemon yellow, and the styles 

 and stigmas usually have the same color as the corolla; but in a 

 small proportion the stigmas are margined with a narrow line of deep 



